Azo dyestuff for dyeing animal fibers in shades of brown



Patented Dec. 5, 1950 AZD DYESTUFF FOB DYEING ANIMAL FIBERS IN SHADES OFBROWN Harold E. Woodward, Penns Grove, N. J assignor to E. I. du Pont deNemours & Company, Wilmington, DeL, a corporation of Delaware NoDrawing. Application October 4, 1947, Serial No. 778,023

1 Claim. 1

Thi invention relates to a novel soluble monazo dye suitable for dyeinganimal fibers, such as wool and hair, in strong shades of brown.

It is among the objects of the present invention to provide a monazodyestuif suitable for dyeing animal fibers in shades of brown. Anotherobject of the invention is to provide such a dyestuff which has goodaflinity for animal fibers and good fastness properties. Other objectsof the invention will be apparent from the following description whichincludes an illustrative embodiment of the invention in which parts areexpressed in parts by weight unless otherwise specified.

Example 1 A solution was made by dissolving 218 grams of the sodium saltof Z-sulfo--nitro-aniline in 2 liters of water at 50 C. The solution wasacidified by adding 2.5 equivalents of hydrochloric acid cooled to C.and the primary arylamine was diazotized in the usual manner by addingone equivalent of sodium nitrite. A solution was made by dissolving 197grams of 1-hydroxy-2- naphthoic acid in two liters of water containing42 grams of sodium hydroxide and 106 grams of sodium carbonate. Couplingin alkaline medium was effected by pouring the diazo solution into thesolution of coupling component. The resulting product of coupling wassalted out at 60 C. and the solids were recovered by filtering. Theproduct was then redissolved in 4 liters of water at 90 C. and 10 gramsof disodium phosphate were added. After stirring one-half hour,activated charcoal and diatomaceous earth were added to clarify thesolution, and the clarified solution was made acid to Congo red forprecipitating the dyestufi. The solid dyestuff was recovered byfiltration, mixed with 80 grams of 2 The product in its acid form isrepresented by the formula (.EOOH

(IJOOH S OsH the disodium salt of said compound being a brown dye forhair and being readily soluble in water. HAROLD E. WOODWARD.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 424,019 Nietzki Mar. 25, 1890743,071 Gley et a1. Nov. 3, 1903 2,333,427 Keller Nov. 2, 1943 FOREIGNPATENTS Number Country Date 219,500 Germany Mar. 2, 1910 OTHERREFERENCES Cain: The Synthetic Dyestuffs, ed. 6, p. 10, 56, Grifiin,London, 1923.

